Test for KT-2619

Remove outdated check in WhenChecker

# KT-2619 fixed

compiler/frontend/src/org/jetbrains/jet/lang/cfg/WhenChecker.java

@@ -49,12 +49,7 @@ public final class WhenChecker {
         ClassDescriptor classDescriptor = (ClassDescriptor) declarationDescriptor;
         if (classDescriptor.getKind() != ClassKind.ENUM_CLASS || classDescriptor.getModality().isOverridable()) return false;
         ClassDescriptor classObjectDescriptor = classDescriptor.getClassObjectDescriptor();
-        //TODO: workaround for KT-2619 Exception on using java enum in when.
-        // should provide correct checks for java enums
-        // may be obsolete once java and kotlin enum work the same way
-        if (classObjectDescriptor == null) {
-            return false;
-        }
+        assert classObjectDescriptor != null : "Enum classes must have class object.";
         JetScope memberScope = classObjectDescriptor.getMemberScope(Collections.<TypeProjection>emptyList());
         Collection<ClassDescriptor> objectDescriptors = memberScope.getObjectDescriptors();
         boolean isExhaust = true;

compiler/testData/diagnostics/tests/j+k/kt2619.kt

@@ -0,0 +1,15 @@
+//FILE: foo.kt
+fun main(args: Array<String>) {
+    val c: Type
+    <!NO_ELSE_IN_WHEN!>when<!> (<!UNINITIALIZED_VARIABLE!>c<!>)  {
+
+    }
+}
+
+
+
+//FILE: Type.java
+public enum Type {
+    TYPE,
+    NO_TYPE;
+}

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -2237,6 +2237,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 doTest("compiler/testData/diagnostics/tests/j+k/kt2606.kt");
             }
             
+            @TestMetadata("kt2619.kt")
+            public void testKt2619() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/j+k/kt2619.kt");
+            }
+            
             @TestMetadata("kt2641.kt")
             public void testKt2641() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/j+k/kt2641.kt");